PHYTOCOENOSES WITH CONVOLVULUS PERSICUS L. ON THE …
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PHYTOCOENOSES WITH CONVOLVULUS PERSICUS L. ON THE WESTERN
COAST OF THE BLACK SEA
M. FĂGĂRAȘa*, L.D. JIANUb
a Ovidius University of Constanța, Faculty of Natural and Agricultural Sciences, University
Street, No. 1, 900470, Constanţa, Romania
E-mail: marius_fagaras@yahoo.com
b Company of Biodiversity Research and Environmental Engineering AON, I.C. Bratianu,
No 131, Constanţa, Romania
Abstract: Field surveys carried out in Romania and Bulgaria between the years 2012 and
2015 led to the identification of phytocoenoses with Convolvulus persicus in some areas of
the Danube Delta Biosphere Reserve (Sulina, Sf. Gheorghe, Cardon), in the natural reserve
Marine Sand Dunes of Agigea and on Durankulak beach, in Northern Bulgaria. Information
regarding floristic composition, ecology and the syntaxonomy of the plant community
Convolvuletum persici (Borza 1931) Sanda et al. 1998 were presented in the paper.
Considerations upon the conservation status and the risk factors which threaten local
populations of Convolvulus persicus on the western Black Sea coast have been given.
Threatened species recorded in the plant association Convolvuletum persici in different
locations in Romania and Bulgaria, as well as the conservation importance of the plant
community, were highlighted in the article.
Keywords: Convolvulus persicus, phytocoenoses, sand dunes, western Black Sea coast
AIMS AND BACKGROUND
Convolvulus persicus (sand morning glory) is a psammophilic species native on the Caspian
Sea littoral, reported in Europe only in Romania, Bulgaria and Turkey1. The general
distribution of this taxa includes different locations around the Black Sea and on the Caspian
Sea2: South-East Romania, Eastern Bulgaria, European Turkey, North-West Anatolia,
Georgia, Russia (Daghestan), Azerbaijan, Iran and Turkmenistan. Because of its rarity, of the
small local populations and of its high vulnerability to the anthropogenic impact, Convolvulus
persicus is considered a Critically Endangered species both in ”The Red Book of the Vascular
Plants of Romania”3 and in ”The Red Data Book of the Republic of Bulgaria”4.
In Romania, Convolvulus persicus has been noticed on the sand dunes in some locations
within the Danube Delta Biosphere Reserve - Sulina, Sfântu Gheorghe, Letea, Caraorman3,
Cardon, C.A. Rosetti, Șfiștofca5, Sacalin6, Perișor7 and in the natural reserve Marine Sand
Dunes of Agigea (Fig. 1).
a b
Fig.1. Distribution area of Convolvulus persicus in Romania and Bulgaria (a = the Danube Delta
Biosphere Reserve; b = southern Romanian coast and northern Bulgarian coast)
In Bulgaria, Convolvulus persicus was recorded in the last 20 years only on the sandy beach
in Durankulak Lake area4. Other locations of this taxa in Bulgaria (near the Rezovska river
mouth, Silistar bay, and Kamchia river estuary) specified in some old papers4 were not
confirmed after 1995. On the Caspian Sea coast, in the North of Iran, the plant community
Convolvuletum persici is mentioned in the Miankaleh Biosphere Reserve8 and in the Boujagh
National Park9. In accordance with the bibliographical sources10, the plant association
Convolvuletum persici (Borza 1931) Sanda et al. 1998 belongs to the order Cakiletalia
maritimae R. Tüxen apud Oberd. 1949 beside other plant communities of the habitat 1210
(Annual vegetation of drift lines).
EXPERIMENTAL
Observations concerning the phytocoenoses with Convolvulus persicus were carried out
between the years 2012 and 2015 on the Black Sea coast of Romania and Bulgaria. Field
observations and phytosociological releves were achieved according to the methodology of
Braun-Blanquet's phytosociological school. The syntaxonomic affiliation of this plant
community is according to the book “Phytocoenoses from Romania”10. The nomenclature of
the species from the floristic composition of the association is in accordance with “Flora
Europaea”1 and “Vascular plants of Romania”11. The conservation status of the species
Convolvulus persicus was assessed based on a 3-level scale as follows: favourable
unfavourable-inadequate and unfavourable-totally inadequate12.
RESULTS AND DISCUSSION
Phytocoenoses with Convolvulus persicus have a fragmented range along the Black Sea shore
and on the marine sandbanks within the Danube Delta Biosphere Reserve. In many locations
of the Danube Delta (Letea, Caraorman, C.A. Rosetti, Șfiștofca, Perișor), Convolvulus
persicus has only small local populations. Typical phytocoenoses with Convolvulus persicus
have been noticed on the sandy beaches of Sulina, Sfântu Gheorghe and Cardon13, in Sacalin-
Zătoane strictly protected area6, in the natural reserve of Agigea and on Durankulak beach, in
northern Bulgaria (Fig. 2). On the wide beaches in Sulina and Sfântu Gheorghe, such types of
phytocoenoses occur on the mobile and semi-fixed sand dunes, approximately 30-40 meters
from the shoreline, where the sea waters reach only during storms.
a b
Fig. 2. Phytocoenoses with Convolvulus persicus on the beaches of Sulina (a) and Durankulak (b)
Convolvulus persicus reach in Sulina a good density of 17-20 individuals/m2. The flowering
period of Convolvulus persicus is in June-July. Only approximately 40-50% of individuals
have bloomed in the investigated period, the vegetative reproduction being prevalent on the
beach of Sulina. The strong attack of the parasitic plant Cuscuta sp. could be the reason for
the low flowering capacity of the sand morning glory in Sulina.
The flowering rate of Convolvulus persicus is higher (approximately 60-70%) on the Sfântu
Gheorghe beach than in Sulina and this fact can be linked to the lower density of the local
populations (10-12 individuals/m2), to the favourable ecological conditions and to a low
anthropogenic pressure upon the dune habitats.
In the coastal area of the Danube Delta, phytocoenoses with Convolvulus persicus are
vulnerable to both anthropogenic and natural pressures such as grazing, tourism, the
expansion of recreational areas on the beaches14, storms15. The conservation status of this
species can be considered favourable in Sfântu Gheorghe and unfavourable-inadequate on the
beach of Sulina where the human impact upon the dune habitats is higher than in Sfântu
Gheorghe. In Sulina, one of the most important touristic gates of the Danube Delta, tourism is
better developed than in Sfântu Gheorghe village and this fact has some negative
consequences on the natural vegetation of the beaches. Approximately 3 hectares of the beach
in Sulina were transformed in 2009 by the local authorities in recreational area. Because of
this situation, Romania was subject to the “infringement procedure” due to the violation of the
European legislation regarding the conservation of the habitats from the Council Directive
92/43/EEC.
On the southern coast of Romania, phytocoenoses with Convolvulus persicus have been
noticed only in the natural reserve Marine Sand Dunes of Agigea, on the mobile sand dunes
from the north-western side of the protected area. Currently, there are different harbour
facilities between the protected area and the seashore which diminished the positive
influences of the sea breezes upon the dune habitats and, consequently, determined significant
microclimate changes in the area of the natural reserve. The steppe grasslands and the
disturbed habitats from the vicinity of the protected area have facilitated the infiltration of
some steppe and ruderal plants, even of some invasive species in the sand dunes complex.
Convolvulus persicus has at present a favourable conservation status only due to some
effective management measures of the dune habitats. The measures consist mainly in
removing the invasive species and of some opportunistic steppe plants from the dunes area.
In Bulgaria, only two phytocoenoses with Convolvulus persicus have been noticed on
Durankulak beach (5 km south from the border with Romania) and these are the only records
on the Bulgarian coast. Convolvulus persicus occupies here approximately 400 square meters
on the first strips of the shifting sand dunes. The flowering rate of this species is very good on
Durankulak beach because more than 70% of the total specimens have bloomed in the period
of survey. Convolvulus persicus has generally a favourable conservation status in Bulgaria,
the risk factors being mainly natural (storms with big waves, strong winds).
The total number of the plant species from the floristic composition of the association is small
(45 taxa) due to the restrictive ecological conditions within the dune habitats area. The
majority of plant species are psammophilic (57.79%) but steppe species are also numerous
(33.33%) (Fig.3). Most of accompanying species belong to the alliances Scabiosion
ucrainicae Boșcaiu 1975, Festucion vaginatae Soó 1929 and Elymion gigantei Morariu 1957.
Convolvulus persicus is the diagnostic taxa of the association Convolvuletum persici and it
has high values of the abundance-dominance index [AD = 3-4] and a high constancy
compared the accompanying species of the plant community (Table 1).
Fig. 3. Comparative values of psammophilic, steppe and invasive species
in the plant association Convolvuletum persici
The species characteristic to the alliance Cakilion maritimae are well represented only on the
beach of Durankulak because here Convolvulus persicus reaches up to 10-15 meters from the
seashore, in the area of the habitat 1210. In the Natural Reserve of Agigea, due to the drier
microclimate, the typical species of the alliances Scabiosion ucrainicae and Festucion
vaginatae have a good occurrence and high value of the abundance-dominance index in the
releves of the association Convolvuletum persici (Table 1).
0,00%
10,00%
20,00%
30,00%
40,00%
50,00%
60,00%
70,00%
psammophilous sp. steppe sp. invasive sp.
ecologic types of species
Table 1. Association table of Convolvuletum persici (Borza 1931) Sanda et al., 1998 Relevé number R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 R11 R12 R13 R14 R15 R16 R17 R18 K Area (m2) 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 Cover (%) 70 80 80 70 50 50 70 70 60 70 60 80 60 60 60 80 70 80 Number of taxa 12 13 12 14 13 15 13 13 12 12 10 11 16 13 11 10 16 11 Characteristic taxa Convolvulus persicus 3 4 4 4 3 3 3 4 3 3 3 4 3 3 3 4 3 4 V Festucetalia vaginatae, Scabiosion ucrainicae Centaurea arenaria subsp. borystenica
+ + + - + + + + + + - + - + - + + - IV
Alyssum hirsutum + + + - - - - - - - + - - 1 1 + 1 + III Cynanchum acutum - - - - + + + - - - + - - - + - + - II Alyssum borzaeanum - - - - - - - - - - - - - - 1 1 2 1 II Silene thymifolia - - + - - - - - - - - - - - - + - + I Carex colchica - - - - - - - - - - - - - - - - - + I Festucion vaginatae+ Bassio laniflorae-Bromion tectorum Secale sylvestre 2 2 2 + 1 + 2 + 1 + + 1 1 2 1 2 + + V Bromus tectorum + + + - 1 + + + + - - - 1 1 + 1 1 1 IV Euphorbia segueriana - + - + - + 2 - 1 - - - - + - + + - III Astragalus varius - 1 - + - - - - - - - - - - + + + + II Silene conica + + + - - - - - - - - - - + + - + - II Plantago arenaria - - - - - - - - - + - - + - - - - + I Corispermum nitidum - - - - - - - - - 1 + + - - - - - - I Apera spica-venti subsp. maritima
- - - - - - - - - - - - 1 - - - - - I
Elymetalia arenariae, Elymion gigantei Eryngium maritimum + + - + + + + - 1 2 1 + + - - - - - IV Leymus racemosus subsp. sabulosus
- + - 1 + + + 1 - 1 + 1 + - - - - - III
Elymus farctus subsp. bessarabicus
1 - - + - - - - - - - - + - - - - - I
Ammophila arenaria subsp. arundinacea
- - + + - - - - - - - - - - - - - I
Polygonum oxyspermum subsp. raii
+ - + - - - - - - - - - - - - - - - I
Cakiletalia maritimae Salsola kali subsp. ruthenica
+ - - + + + - - + + - + - - - - - - III
Cakile maritima subsp. 1 1 + - - - - - - - - - - - - - - - I
euxina Crambe maritima 1 - + - - - - - - - - - - - - - - - I Lactuca tatarica - - - + - - - - - - - - - - - - - - I Scolymus hispanicus - - - - - - - - - - - - + - - - - - I Festucetalia valesiacae + Festucion rupicolae Medicago falcata - - - + - + - - - - + - - + 1 + + + III Linaria genistifolia subsp. euxina
- + + + - + - + - - - - - + - - + - II
Linum austriacum - - - - - + - + + - - - + + - - - - II Crepis foetida subsp. rhoeadifolia
- - - + - + - + - - - - + + - - - - II
Seseli tortuosum - - - - - - - + - - - - - - - - + + I Cerastium brachypetalum - - - - - - - - - - - - - - + - + - I Cynodon dactylon - - - - - - + - + - - 1 - + - - - - I Verbascum banaticum - - - - - - - + + - - - - - - - - - I Cichorium intybus - - - - - - + - - - - - - - - - - - I Other species Xanthium italicum - + - + + 2 + - 1 1 + + - + - - - - III Hippophae rhamnoides - - - - 1 - 1 - - - - + 1 - - - - - II Elaeagnus angustifolia - - - - + - + - - + - - + - - - - - II Tamarix ramosissima - - - - + - - - - + - - + - - - - - I Senecio vernalis - - - - + - - - - - - - - - + - + - I Cuscuta sp. - - - - - - - - - + + 1 - - - - - - I Conyza canadensis - - - - - - - - + - - - + - - - - - I Petasites spurius - - - - - + - + - - - - - - - - - - I Amorpha fruticosa - - - - - - - - - - - - + - - - - - I Calamagrostis epigejos - - - - - - - + - - - - - - - - - - I Papaver rhoeas - - - - - - - - - - - - - - - - + - I Teucrium chamaedrys - - - - - - - + - - - - - - - - - - I Location of the releves: Durankulak beach, Bulgaria (R1-4); Sfântu Gheorghe, Danube Delta (R5-9); Sulina, Danube Delta (R10-13); Cardon, Danube Delta (R14); Marine Sand Dunes Reserve, Agigea (R15-18);
In the phytocoenoses with Convolvulus persicus from the Danube Delta, the species
belonging to the class Ammophiletea Br.-Bl. et R. Tüxen 1943 are better represented than in
Durankulak and Agigea. Here, Convolvulus persicus occupies the basis of the sand dunes with
Leymus sabulosus, Eryngium maritimum and Elymus farctus subsp. bessarabicus.
The invasive and potentially invasive plants (Amorpha fruticosa, Conyza canadensis), with
the exception of Xanthium italicum have a low occurrence in the releves of the association
Convolvuletum persici (Table 1). Xanthium italicum, an invasive species in the sand dunes
area, represents one of the threats for the population of Convolvulus persicus in the long term.
Parasitic species from the genus Cuscuta are another major threat for the populations of
Convolvulus persicus, mainly on the beach of Sulina.
Twelve threatened plant species according to The Red Book of the vascular plants of
Romania3, the Red Data Book of the Republic of Bulgaria4 and the Red List of Bulgarian
vascular plants16, have been recorded in the phytocoenoses with Convolvulus persicus:
Alyssum borzaeanum (CR in Romania, EN in Bulgaria), Convolvulus persicus (CR in
Romania, EN in Bulgaria), Silene thymifolia (VU in Romania, EN in Bulgaria), Eryngium
maritimum (VU in Romania, EN in Bulgaria), Elymus farctus subsp. bessarabicus (CR in
Romania), Petasites spurius (CR in Romania), Cakile maritima subsp. euxina (EN in
Romania), Crambe maritima (EN in Romania), Polygonum oxyspermum subsp. raii (syn.
Polygonum mesembricum) (VU in Romania, NT in Bulgaria), Astragalus varius (VU in
Romania), Scolymus hispanicus (VU in Romania), Ammophila arenaria subsp. arundinacea
(CR according to Ref. 3, but most probably already extinct in Romania).
Species such as Ammophila arenaria subsp. arundinacea, Polygonum oxyspermum subsp.
raii, Cakile maritima subsp. euxina and Crambe maritima have been recorded only on
Durankulak beach while Alyssum borzaeanum, Petasites spurius and Scolymus hispanicus
were noticed only in the releves in Romania.
Of the twelve threatened taxa, five are Critically Endangered (in Romania), six are
Endangered (4 in Bulgaria and 2 in Romania), five are Vulnerable (in Romania) and one is
Near Threatened (in Bulgaria) (Fig. 4).
Fig. 4. Number of species belonging to different Red Data Categories in Romania and Bulgaria (CR-
Critically Endangered, EN-Endangered, VU-Vulnerable, NT-Near Threatened)
The high percentage of rare species (26%), compared with the total number of recorded taxa
within the plant association (46 taxa), emphasizes the conservation importance of the plant
community Convolvuletum persici. According to Table 1, the most numerous rare plants are
on the beach of Durankulak (9 taxa) and fewer of them on the beach of Sulina (4 taxa), in the
natural reserve of Agigea (4 taxa) and on the beach of Sfântu Gheorghe (3 taxa).
CONCLUSIONS
Phytocoenoses with Convolvulus persicus are very rare on the western coast of the Black Sea.
Such type of plant communities have been noticed in the Danube Delta, in the natural reserve
of Agigea and on Durankulak beach in Bulgaria.
The plant association Convolvuletum persici can be generally found in the habitat 2110 but on
the Durankulak beach, phytocoenoses with Convolvulus persicus reach the area of habitat
1210.
In the Danube Delta Biosphere Reserve, the phytocoenoses with Convolvulus persicus are
vulnerable mainly to anthropogenic pressures such as grazing, tourism or expansion of the
0
1
2
3
4
5
6
CR EN VU NT
Ro
Bg
recreational areas on the beaches. The parasitic plant Cuscuta sp. is another serious threat for
the local populations of Convolvulus persicus, especially on the beach of Sulina.
On the southern coast of Romania, Convolvulus persicus is well preserved in the Natural
Reserve of Agigea where its favourable conservation status is a consequence of some
effective management measures for the dune habitats.
The Durankulak beach is currently the only location in Bulgaria in which Convolvulus
persicus was confirmed in the last twenty years; here, it has a favourable conservation status
in the frame of the Nature 2000 protected site BG0000154 Ezero Durankulak.
The ecological preferences of Convolvulus persicus for the dune habitats and the
syntaxonomic affiliation of the accompanying species indicate that the association
Convolvuletum persici should rather be included in the order Festucetalia vaginatae Soó 1957
than in Cakiletalia maritimae R. Tx. apud Oberd. 1949.
Aknowledgements. The study has been supported by the grants PN–II–PT–PCCA–2011–
3.2–1427 No.69/2012 (ECOMAGIS) financed by the UEFISCDI and
EASME/EMFF/2014/1.2.1.5/2/SI2.707672 MSP LOT 1 BLACK SEA (MARSPLAN-BS)
financed by European Commission.
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